Authorities formally arrested 23-year-old Ciancia over the attack. He has been charged with the murder of federal officer and commission of violence at an international airport.

Advertisement

Under the specified charges, federal prosecutors could seek the death penalty.

Hundreds of Los Angeles International Airport staff have today begun the almost impossible task of re-scheduling some of the more than 1550 flights and 160,000 passengers affected by yesterday's deadly shooting.

Investigators, meanwhile, are attempting to piece together a mosiac of the 23-year-old man who walked into a crowded terminal with an automatic assault rifle and opened fire, hoping to understand more about his background and his motive.

Hernandez is the first TSA agent killed in the line of duty and Los Angeles Police Department officers are today wearing black armbands in his honour. Los Angeles Mayor Eric Garcetti has also ordered that flags on city buildings be flown at half-mast.

The TSA was formed in the wake of the September 11, 2011 terrorist attacks on New York to protect US airports.

When he opened fire, witnesses said Ciancia was yelling. But as he walked down the narrow concourse of LAX's terminal 3, another witness, Leon Saryan, who came face to face with the gunman, said he was calm.

"He was walking slowly," Saryan said. "He must have felt that he was in control, because he had his weapon and nobody else did at that time."

Another passenger, 26-year-old Stephanie Rosemeyer, said that as panic spread, she found herself face to face with Ciancia.

"We made eye contact," she told Reuters. "He just looked so, so angry. You know that look that people get when they're just beyond anything that they can handle."

Investigators say Ciancia had been carrying a note with "anti-government" and "anti-TSA" messages.

One report said the note made specific reference to how Ciancia believed his constitutional rights were being violated by TSA searches.

In the note he described himself as a "pissed-off patriot". He reportedly also named former Department of Homeland Security Secretary Janet Napolitano in the note.

Several media reports have said the note ended with the letters "NWO", an apparent reference to the "new world order".

The "new world order" is a conspiracy theory which supposes a powerful elite is secretly controlling world events for the purpose of establishing a single global government.

Despite media reports to the contrary, Ciancia was not a former or current TSA agent.

Early reports suggested he might have been, but a spokesman for the American Federation of Government Employees organisation, Tim Kauffman, which represents the TSA's staff of more than 45,000, confirmed Ciancia was not now, or previously, a TSA officer.

Ciancia was, by all accounts, a shy man with no apparent criminal history.

He attended Salesianum School, an all-boys Roman Catholic school in Wilmington, Delaware. He was described by one former classmate as a loner who was bullied.

"In four years, I never heard a word out of his mouth. I really don't remember any one person who was close to him," David Hamilton told The Los Angeles Times.

Cianca graduated in 2008.

A neighbour of the family home in Pennsville, New Jersey, Joshua Pagan, speaking to the US network NBC, said: "Not in a million years would I ever believe anyone from that family, or even this town. Nothing ever happens here."

Authorities were first alerted to a possible problem the day before when Ciancia's family contacted the LAPD because of text messages he had been sending them.

Although Ciancia did not explicity use the word "suicide", his family feared he was going to harm himself.

A police unit was sent to Ciancia's house to check on his welfare. His flatmates told police Ciancia was fine and his behaviour had not been unusual.

The events of yesterday morning would quickly undermine that assertion.

A day later, LAX is still only partially re-opened.

The "ground stop" order, which effectively closed the airport to incoming and outgoing air traffic, was lifted at 4pm yesterday but some airlines, particularly Virgin Australia and Virgin America, which were based in terminal 3, are still affected.

Passengers in terminal 3 who abandoned baggage in the chaos are yet to retrieve their belongings. The FBI has advised those items must remain at the crime scene until their investigation is complete.

The American Red Cross has established an operation at the airport to assist displaced passengers, and staff from Los Angeles County Department of Mental Health are also on-site offering assistance to passengers or airport employees experiencing emotional distress.

A spokesman for LAX said the airport should resume close to full operation within the next day.

3 Nov
An Australian student who was in a Virgin America lounge at Los Angeles International Airport as a gunman opened fire in the terminal, killing a security officer, has given a detailed account of the fear and panic of passengers waiting for flights.

2 Nov
The New Jersey man who was shot and arrested after killing a Transportation Security Administration officer was remembered by neighbours as ''just a normal kid'' who attended the local high school and worked in his father's car repair shop.